DISEASES OF MARINE FISHES
7
in American plaice, Hippoglossoides platessoides (Fabr.), of the Grand
Bank was reported by Templeman (1965b). Infected fish were first seen
in 1960, and in 1964 the infection level in American plaice on the eastern
slope of the Grand Bank was approximately lo/. Badly infected fish,
called " scabby " or " seedy " by fishermen, were thrown overboard,
and estimates of such discards ran as high as 300-400 pounds per set in
areas of heavy infections. Trawlers usually moved to other locations
where fewer fish were diseased. Templeman suggested several possible
explanations for the outbreak, including the possibility that the disease
is enzootic in the population and may increase in intensity periodically.
Nordenberg (1962) found infections as high as 12% in flounders,
Pleuronectes Jlesus, from the Oresund, with some indication of higher
prevalence in the warmer months of the year.
Neoplastic or hyperplastic diseases, some thought to be of virus
origin, include dermal and epidermal papillomas of many flatfish
species (Fig. lb). Such diseased conditions have been reported from :
halibut, Hippoglossus hippoglossus L., by Johnstone (1912a) ; plaice,
Pleuronectes platessa (L.), by Johnstone (1925); sole, Solea solea (L.), by
Thomas (1926) ; winter flounder, Pseudopleuronectes americanus (Walb.),
by Smith (1935) ; flathead sole, Hippoylossoides elnssodon Jord. and
Gilb., by Wellings and Chuinard (1964) and Wellings et al. (1964); as
well as from other pleuronectids. Suspected viral particles have been
described from the cytoplasm, but transmission has not been reported.
Similar epidermal hyperplasia, of suspected viral etiology, is common
in fresh water among European cyprinids. Characterized by irregular
white raised patches on the skin, the disease is often referred to as
" fish pox " (Roegner-Aust and Schleich, 1951 ; Roegner-Aust, 1953).
A remarkable tumorous growth of eels is aptly labelled " Blumenkohlkrankheit " or " cauliflower disease " (Fig. lc). This common
chronic fibro-epithelial tumor, often of dramatic proportions, occurs
principally in the head region of European eels, Anguilln anguilla (L.).
Reports of the disease in European rivers and coastal waters have
increased in recent years (Schaperclaus, 1954 ; Liihmann and Mann,
1957 ; Engelbrecht, 1958). Transmission has not yet been effected,
but virus etiology is strongly suspected (Christiansen and Jensen, 1950).
Eels with progressive tumors become emaciated and die. Schaperclaus
(1953a) also found comparable growths in cod, Godus niorhun L., and
papillomas have been reported from smelts, Osmerus eperlanus (L.),
taken in the Baltic Sea with characteristics very similar to cauliflower
disease of eels (Breslauer, 191 6).
A number of highly pathogenic viruses of fresh-water fishes do not
cause tumors (Wolf, 1964). The diseases produced include infectious
A.Y.B.-4
n
7
in American plaice, Hippoglossoides platessoides (Fabr.), of the Grand
Bank was reported by Templeman (1965b). Infected fish were first seen
in 1960, and in 1964 the infection level in American plaice on the eastern
slope of the Grand Bank was approximately lo/. Badly infected fish,
called " scabby " or " seedy " by fishermen, were thrown overboard,
and estimates of such discards ran as high as 300-400 pounds per set in
areas of heavy infections. Trawlers usually moved to other locations
where fewer fish were diseased. Templeman suggested several possible
explanations for the outbreak, including the possibility that the disease
is enzootic in the population and may increase in intensity periodically.
Nordenberg (1962) found infections as high as 12% in flounders,
Pleuronectes Jlesus, from the Oresund, with some indication of higher
prevalence in the warmer months of the year.
Neoplastic or hyperplastic diseases, some thought to be of virus
origin, include dermal and epidermal papillomas of many flatfish
species (Fig. lb). Such diseased conditions have been reported from :
halibut, Hippoglossus hippoglossus L., by Johnstone (1912a) ; plaice,
Pleuronectes platessa (L.), by Johnstone (1925); sole, Solea solea (L.), by
Thomas (1926) ; winter flounder, Pseudopleuronectes americanus (Walb.),
by Smith (1935) ; flathead sole, Hippoylossoides elnssodon Jord. and
Gilb., by Wellings and Chuinard (1964) and Wellings et al. (1964); as
well as from other pleuronectids. Suspected viral particles have been
described from the cytoplasm, but transmission has not been reported.
Similar epidermal hyperplasia, of suspected viral etiology, is common
in fresh water among European cyprinids. Characterized by irregular
white raised patches on the skin, the disease is often referred to as
" fish pox " (Roegner-Aust and Schleich, 1951 ; Roegner-Aust, 1953).
A remarkable tumorous growth of eels is aptly labelled " Blumenkohlkrankheit " or " cauliflower disease " (Fig. lc). This common
chronic fibro-epithelial tumor, often of dramatic proportions, occurs
principally in the head region of European eels, Anguilln anguilla (L.).
Reports of the disease in European rivers and coastal waters have
increased in recent years (Schaperclaus, 1954 ; Liihmann and Mann,
1957 ; Engelbrecht, 1958). Transmission has not yet been effected,
but virus etiology is strongly suspected (Christiansen and Jensen, 1950).
Eels with progressive tumors become emaciated and die. Schaperclaus
(1953a) also found comparable growths in cod, Godus niorhun L., and
papillomas have been reported from smelts, Osmerus eperlanus (L.),
taken in the Baltic Sea with characteristics very similar to cauliflower
disease of eels (Breslauer, 191 6).
A number of highly pathogenic viruses of fresh-water fishes do not
cause tumors (Wolf, 1964). The diseases produced include infectious
A.Y.B.-4
n